366 REPORT OF NATIONAL MUSEUM, 1!)04. 



Such being the case, it is worthy of remark that he regarded the then 

 customary (and to some extent still prevailing) habit of exaggerating 



the vertical relief as "a hideous burlesque upon the 

 First Geological actual aspect of the district represented or, rather, 



misrepresented," and that he had himself "for some 

 time ceased to make any such difference between the horizontal and 

 vertical scale. " Ta} 7 lor, it should be noted, was particularly active 

 during the period 1831 to 1839, his papers relating almost wholly to 

 economic problems and appearing largely in the Transactions of the 

 Geological Society of Pennsylvania. His most pretentious publica- 

 tion was that entitled Statistics of Coal, a volume of 751 pages relating 

 to the coal fields of the world, published in 1818. 



Troost's sixth annual report as State geologist of Tennessee, a 

 pamphlet of 18 pages, was made in October, 1811; his seventh, of 15 

 pages, in 1813; the eighth, of but 20 pages, in 1815; and the ninth and 



last in 1818. During the interval between his fifth and 

 Ten^fesse^TsVi! sixth reports he had become acquainted with the work 



of Sedgwick and Murchison in England, and the result 

 is a slight modification of his views regarding the rocks of Tennessee. 

 He now announced the conclusion that those rocks west of the line which 

 separated Tennessee from the State of North Carolina, and previously 

 classitied by him as transition under the names of graywacke, etc., 

 belong to Sedgwick's Cambrian system. The range known b} T the 

 name of Bays Mountains, which extends into Tennessee for about 100 

 miles in a northeast and southwest direction, he believed to terminate 

 this system toward the we^t. A few pages farther on he, however, 

 thrust a doubt on this determination by writing: 



I consider * * * that Bays Mountain forms the upper part of the Cambrian 

 system or that it perhaps belongs to the Old Red Sandstone; that thence toward the 

 north of that mountain chain another formation commences, which is the Silurian 

 system of Murchison. 



To which of his particular subdivisions they should belong he was 

 in doubt. He felt, however, it was possible they might be the equiva- 

 lent of Murchison's Llandeilo flags (Upper Cambrian). 



The oolitic limestones and siliceous strata toward the west of the 

 Cumberland Mountains he thought to rest upon a continuation of the 

 Silurian system, more generally known under the name of "mountain 

 limestone.' 1 This he made to extend over the whole of middle Tennes- 

 see to a few miles east of the Tennessee River. 



In his seventh annual report he announced that the region about 

 Nashville was composed of strata belonging to the Silurian system, 

 and mentioned the fossils which he considered as characteristic of the 

 lowest strata. In this report he gave a detail colored geological map 

 of Davidson. Williamson, and Maury counties. 



Troost's collection of fossil Echinodermata containing all his types 

 and species described in what is known as Troost's list of 1850, 



